Technical Field
The present disclosure relates to a stator of a rotating electric machine that is mounted in a vehicle or the like, and used as an electric motor or a power generator.
Related Art
As a rotating electric machine that is used so as to be mounted in a vehicle, a rotating electric machine that includes a rotor provided in a rotatable manner, and a stator having a stator core and a stator winding is commonly known. In this rotating electric machine, the stator core is disposed so as to oppose the rotor in a radial direction and has a plurality of slots that are arrayed in a circumferential direction, and the stator winding is composed of a plurality of phase windings that are wound around the slots in the stator core.
The stator core is ordinarily formed by a plurality of steel plates that are laminated in an axial direction to prevent generation of eddy currents. In addition, JP-A-2013-211945 discloses a motor (electric motor) that includes a bus bar, that connects the plurality of phase windings that are wound around the slots of the stator core.
As the stator winding, for example, a segment type is known in which the stator winding is wound around the stator core by open end portions of U-shaped conductor segments being inserted into the slots of the stator core, and the ends of predetermined open end portions extending from differing slots being connected to each other on one end side of the stator core.
In addition, JP-A-2005-12961 discloses that a guiding groove is provided on the outer circumferential surface of a coil end portion of the stator winding that projects outward from an axial direction end surface of the stator core, to guide a cooling liquid supplied from the coil end portion.
The bus bar disclosed in above-mentioned JP-A-2013-211945 may become damaged as a result of stress attributed to temperature difference caused by the difference in density of the current flowing through the bus bar.
In addition, when the bus bar is attached to the stator core, as shown in FIG. 27, the bus bar is attached by metal attachment pins 1167 provided in the bus bar being pressed in an axial direction into attachment holes 1135 provided in a plurality of areas on one axial-direction end surface of a stator core 1130. However, when the attachment pins 1167 are pressed into the attachment holes 1135 in the stator core 130, the steel plates of the stator core 1130 that are laminated in the axial direction conduct current amongst one another via the attachment pins 1167. As a result, eddy currents that pass through the attachment pins 1167 are generated, and loss increases.
In addition, as a winding method for the stator winding that is wound around the stator core, “distributed winding” in which the winding is not concentrated at a single slot, but rather distributed among a plurality of slots is known. In the stator winding that is wound around the stator core by distributed winding, in particular, phase windings of differing phases that have a large potential difference are near each other at the coil end portion. Therefore, when the insulation capability of an insulating film that covers the outer circumferential surface of a conductor line decreases as a result of abnormal heat generation or thermal degradation, insulation defects may occur.
Therefore, it is desired to provide a stator of a rotating electric machine that is capable of suppressing differences in current density within the bus bar and reducing stress attributed to temperature difference.
In addition, it is desired to provide a stator of a rotating electric machine that is capable of suppressing generation of eddy currents that flow through the attachment pins of the bus bar that are pressed into the attachment holes in the stator core, and suppressing increase in loss.
In addition, it is desired to provide a stator of a rotating electric machine that is capable of preventing temperature rise in the stator winding and preventing the occurrence of insulation defects.